J/ApJ/682/1217 Abundances in red giants in 7 globular clusters (Kirby+, 2008)
Metallicity and alpha-element abundance measurement in red giant stars from medium-resolution spectra. Kirby E.N., Guhathakurta P., Sneden C. <Astrophys. J., 682, 1217-1233 (2008)> =2008ApJ...682.1217K
ADC_Keywords: Clusters, globular ; Abundances, [Fe/H] ; Photometry, UBVRI ; Stars, giant ; Spectroscopy Keywords: globular clusters: individual (M13, M15, M71, M79, NGC 2419, NGC 7006, NGC 7492) - stars: abundances Abstract: We present a technique that applies spectral synthesis to medium-resolution spectroscopy (MRS; R∼6000) in the red (6300Å<λ<9100Å) to measure [Fe/H] and [α/Fe] of individual red giant stars over a wide metallicity range. We apply our technique to 264 red giant stars in seven Galactic globular clusters and demonstrate that it reproduces the metallicities and α-enhancements derived from high-resolution spectroscopy (HRS). The MRS technique excludes the three CaII triplet lines and instead relies on a plethora of weaker lines. Unlike empirical metallicity estimators, such as the equivalent width of the CaII triplet, the synthetic method presented here is applicable over an arbitrarily wide metallicity range and is independent of assumptions about the α-enhancement. Description: We present observations of seven globular clusters with the Deep Imaging Multi-Object Spectrometer (DEIMOS) on the Keck II telescope, in 2006 Feb 2, 2007 Oct 12 and 2007 Nov 13,14,15. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 31 48236 Line list table6.dat 155 264 Abundances for individual stars
See also: II/248 : UBV photometry and proper motions in M13 (Kadla, 1966) J/A+A/505/117 : Abundances of red giants in 15 globular clusters (Carretta+, 2009) J/A+A/505/139 : Abundances of red giants in 17 globular clusters (Carretta+, 2009) J/A+A/486/941 : Abundances in M71 (NGC 6838) (Alves-Brito+, 2008) J/AJ/129/1607 : Equivalent widths of 4 RGB in NGC 7492 (Cohen+, 2005) J/PASP/117/37 : BVRI photometry in NGC 2419, Pal 4, and Pal 14 (Saha+, 2005) J/A+AS/144/227 : BV photometry of M71 (Geffert+, 2000) J/AJ/112/601 : UV photometry in M79 (Hill+ 1996) J/AJ/107/230 : BVRI CCD photometry of NGC 1904 (Alcaino+, 1994) J/A+AS/26/353 : UBV observations in globular NGC 1904 (Alcaino+, 1976) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 8 F8.3 0.1nm lambda Wavelength in Angstroms 10- 16 F7.3 --- Ion Species identification (1) 18- 23 F6.3 eV ExPot Excitation potential (2) 25- 31 F7.3 [-] log(gf) Log of oscillator strength (3)
Note (1): A code representing the atomic or molecular species. The integer part of the code is the element's atomic number. Codes greater than 100 represent molecules. For example, 607 represents CN. The first decimal place of the code is the ionization state, where 0 is neutral. Remaining decimal places are mass numbers for isotopic hyperfine transitions. Note (2): Any Fe I line with fewer than three decimal places of excitation potential is invented to account for a line in the Sun and/or Arcturus. Note (3): The transitions that we modified have oscillator strengths with fewer than three decimal places.
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Cluster Cluster name 10- 11 I2 h RAh Hour of Right Ascension (J2000) 13- 14 I2 min RAm Minute of Right Ascension (J2000) 16- 19 F4.1 s RAs Second of Right Ascension (J2000) 21 A1 --- DE- Sign of the Declination (J2000) 22- 23 I2 deg DEd Degree of Declination (J2000) 25- 26 I2 arcmin DEm Arcminute of Declination (J2000) 28- 29 I2 arcsec DEs Arcsecond of Declination (J2000) 31- 35 F5.2 mag Bmag ? B band magnitude (1) 37- 40 F4.2 mag e_Bmag ? Uncertainty in Bmag (1) 42- 46 F5.2 mag Vmag V band magnitude (1) 48- 51 F4.2 mag e_Vmag Uncertainty in Vmag (1) 53- 57 F5.2 mag Imag ? I band magnitude (1) 59- 62 F4.2 mag e_Imag ? Uncertainty in Imag (1) 64- 67 I4 K Teff Effective temperature 69- 72 F4.2 [cm/s2] log(g) Log of surface gravity 74- 78 F5.2 [Sun] [Fe/H]M Metallicity from Medium resolution spectroscopy 80- 83 F4.2 [Sun] e_[Fe/H]M Uncertainty in [Fe/H]M 85- 89 F5.2 [Sun] [a/Fe]M α enhancement from Medium resolution spectroscopy 91- 94 F4.2 [Sun] e_[a/Fe]M Uncertainty in [a/Fe]M 96-100 F5.2 [Sun] [Fe/H]H ? Metallicity from High resolution spectroscopy 102-105 F4.2 [Sun] e_[Fe/H]H ? Uncertainty in [Fe/H]H 107-111 F5.2 [Sun] [a/Fe]H ? alpha enhancement from High resolution spectroscopy (2) 113-116 F4.2 [Sun] e_[a/Fe]H ? Uncertainty in [a/Fe]H 118-135 A18 --- HRSaut High resolution spectroscopy author's reference 137-155 A19 --- BibCode High resolution spectroscopy bibcode
Note (1): P. B. Stetson has generously provided this photometry, which is preliminary pending his own publication of these data. Note (2): See Section 5.3 for a discussion on [α/Fe]HRS measurements of Sneden et al., 1997AJ....114.1964S, Sneden et al., 2000AJ....120.1351S and Sneden et al., 2004AJ....127.2162S.
Nomenclature note: Individual stars are <[KGS2008] JHHMMSS.s+DDMMSS> in Simbad. History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 24-Nov-2010
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